import {Pos} from "../line/pos.js"
import {visualLine} from "../line/spans.js"
import {getLine} from "../line/utils_line.js"
import {
    charCoords,
    cursorCoords,
    displayWidth,
    paddingH,
    wrappedLineExtentChar
} from "../measurement/position_measurement.js"
import {getOrder, iterateBidiSections} from "../util/bidi.js"
import {elt} from "../util/dom.js"

export function updateSelection(cm) {
    cm.display.input.showSelection(cm.display.input.prepareSelection())
}

export function prepareSelection(cm, primary = true) {
    let doc = cm.doc, result = {}
    let curFragment = result.cursors = document.createDocumentFragment()
    let selFragment = result.selection = document.createDocumentFragment()

    for (let i = 0; i < doc.sel.ranges.length; i++) {
        if (!primary && i == doc.sel.primIndex) continue
        let range = doc.sel.ranges[i]
        if (range.from().line >= cm.display.viewTo || range.to().line < cm.display.viewFrom) continue
        let collapsed = range.empty()
        if (collapsed || cm.options.showCursorWhenSelecting)
            drawSelectionCursor(cm, range.head, curFragment)
        if (!collapsed)
            drawSelectionRange(cm, range, selFragment)
    }
    return result
}

// Draws a cursor for the given range
export function drawSelectionCursor(cm, head, output) {
    let pos = cursorCoords(cm, head, "div", null, null, !cm.options.singleCursorHeightPerLine)

    let cursor = output.appendChild(elt("div", "\u00a0", "CodeMirror-cursor"))
    cursor.style.left = pos.left + "px"
    cursor.style.top = pos.top + "px"
    cursor.style.height = Math.max(0, pos.bottom - pos.top) * cm.options.cursorHeight + "px"

    if (pos.other) {
        // Secondary cursor, shown when on a 'jump' in bi-directional text
        let otherCursor = output.appendChild(elt("div", "\u00a0", "CodeMirror-cursor CodeMirror-secondarycursor"))
        otherCursor.style.display = ""
        otherCursor.style.left = pos.other.left + "px"
        otherCursor.style.top = pos.other.top + "px"
        otherCursor.style.height = (pos.other.bottom - pos.other.top) * .85 + "px"
    }
}

function cmpCoords(a, b) {
    return a.top - b.top || a.left - b.left
}

// Draws the given range as a highlighted selection
function drawSelectionRange(cm, range, output) {
    let display = cm.display, doc = cm.doc
    let fragment = document.createDocumentFragment()
    let padding = paddingH(cm.display), leftSide = padding.left
    let rightSide = Math.max(display.sizerWidth, displayWidth(cm) - display.sizer.offsetLeft) - padding.right
    let docLTR = doc.direction == "ltr"

    function add(left, top, width, bottom) {
        if (top < 0) top = 0
        top = Math.round(top)
        bottom = Math.round(bottom)
        fragment.appendChild(elt("div", null, "CodeMirror-selected", `position: absolute; left: ${left}px;
                             top: ${top}px; width: ${width == null ? rightSide - left : width}px;
                             height: ${bottom - top}px`))
    }

    function drawForLine(line, fromArg, toArg) {
        let lineObj = getLine(doc, line)
        let lineLen = lineObj.text.length
        let start, end

        function coords(ch, bias) {
            return charCoords(cm, Pos(line, ch), "div", lineObj, bias)
        }

        function wrapX(pos, dir, side) {
            let extent = wrappedLineExtentChar(cm, lineObj, null, pos)
            let prop = (dir == "ltr") == (side == "after") ? "left" : "right"
            let ch = side == "after" ? extent.begin : extent.end - (/\s/.test(lineObj.text.charAt(extent.end - 1)) ? 2 : 1)
            return coords(ch, prop)[prop]
        }

        let order = getOrder(lineObj, doc.direction)
        iterateBidiSections(order, fromArg || 0, toArg == null ? lineLen : toArg, (from, to, dir, i) => {
            let ltr = dir == "ltr"
            let fromPos = coords(from, ltr ? "left" : "right")
            let toPos = coords(to - 1, ltr ? "right" : "left")

            let openStart = fromArg == null && from == 0, openEnd = toArg == null && to == lineLen
            let first = i == 0, last = !order || i == order.length - 1
            if (toPos.top - fromPos.top <= 3) { // Single line
                let openLeft = (docLTR ? openStart : openEnd) && first
                let openRight = (docLTR ? openEnd : openStart) && last
                let left = openLeft ? leftSide : (ltr ? fromPos : toPos).left
                let right = openRight ? rightSide : (ltr ? toPos : fromPos).right
                add(left, fromPos.top, right - left, fromPos.bottom)
            } else { // Multiple lines
                let topLeft, topRight, botLeft, botRight
                if (ltr) {
                    topLeft = docLTR && openStart && first ? leftSide : fromPos.left
                    topRight = docLTR ? rightSide : wrapX(from, dir, "before")
                    botLeft = docLTR ? leftSide : wrapX(to, dir, "after")
                    botRight = docLTR && openEnd && last ? rightSide : toPos.right
                } else {
                    topLeft = !docLTR ? leftSide : wrapX(from, dir, "before")
                    topRight = !docLTR && openStart && first ? rightSide : fromPos.right
                    botLeft = !docLTR && openEnd && last ? leftSide : toPos.left
                    botRight = !docLTR ? rightSide : wrapX(to, dir, "after")
                }
                add(topLeft, fromPos.top, topRight - topLeft, fromPos.bottom)
                if (fromPos.bottom < toPos.top) add(leftSide, fromPos.bottom, null, toPos.top)
                add(botLeft, toPos.top, botRight - botLeft, toPos.bottom)
            }

            if (!start || cmpCoords(fromPos, start) < 0) start = fromPos
            if (cmpCoords(toPos, start) < 0) start = toPos
            if (!end || cmpCoords(fromPos, end) < 0) end = fromPos
            if (cmpCoords(toPos, end) < 0) end = toPos
        })
        return {start: start, end: end}
    }

    let sFrom = range.from(), sTo = range.to()
    if (sFrom.line == sTo.line) {
        drawForLine(sFrom.line, sFrom.ch, sTo.ch)
    } else {
        let fromLine = getLine(doc, sFrom.line), toLine = getLine(doc, sTo.line)
        let singleVLine = visualLine(fromLine) == visualLine(toLine)
        let leftEnd = drawForLine(sFrom.line, sFrom.ch, singleVLine ? fromLine.text.length + 1 : null).end
        let rightStart = drawForLine(sTo.line, singleVLine ? 0 : null, sTo.ch).start
        if (singleVLine) {
            if (leftEnd.top < rightStart.top - 2) {
                add(leftEnd.right, leftEnd.top, null, leftEnd.bottom)
                add(leftSide, rightStart.top, rightStart.left, rightStart.bottom)
            } else {
                add(leftEnd.right, leftEnd.top, rightStart.left - leftEnd.right, leftEnd.bottom)
            }
        }
        if (leftEnd.bottom < rightStart.top)
            add(leftSide, leftEnd.bottom, null, rightStart.top)
    }

    output.appendChild(fragment)
}

// Cursor-blinking
export function restartBlink(cm) {
    if (!cm.state.focused) return
    let display = cm.display
    clearInterval(display.blinker)
    let on = true
    display.cursorDiv.style.visibility = ""
    if (cm.options.cursorBlinkRate > 0)
        display.blinker = setInterval(() => display.cursorDiv.style.visibility = (on = !on) ? "" : "hidden",
            cm.options.cursorBlinkRate)
    else if (cm.options.cursorBlinkRate < 0)
        display.cursorDiv.style.visibility = "hidden"
}
